Light Detection and Ranging (LIDAR), is a remote sensing method that uses light in the form of a pulsed laser to measure ranges (variable distances) to an object. In particular, light is transmitted towards the object and the time it takes to return to its source is measured. This is also referred to as measuring time-of-flight (TOF).
LIDAR sensors are an essential element in future fully autonomous or semi-autonomous self-driving cars. The system operates on the principle of TOF measurement. A very short laser pulse is transmitted, hits an object, is reflected and detected by a sensor. From the time-of-flight of the laser beam it is possible to calculate the distance to the object. Scanning LIDAR systems scan the surroundings of the car horizontally with a laser beam across a certain angular segment and produce a three-dimensional (3D) map of the environment. Conventional systems use rotating mirrors which are not integrated on chip level. Some solutions make use of several laser diodes mounted one on top of the other to extend the vertical field of view.
In LIDAR systems, packaging of the MEMS chip should reduce or eliminate static reflection back onto the MEMS micro-mirror that would otherwise cause inaccuracies, including a “blurring” in the return image caused by “ghost” beams.